Homebuilt Rov Forum

Just curious what power sources everyone has used successfully. Run a line or manage an onboard battery? I'm really looking at batteries myself and mainly looking at type, weight, and Ah?

Well Shawn I can say that I have been using just a regular riding tractor battery for three years now and it works just fine, although this fall I discovered that it needed a charge and that was that.

Shawn, I use a big fat 125 amp hr deep cycle batt topside.
It's a beast @ 70lbs but it gives me all the power I need.
On my next rov I think I'll try an on board SLA and save the
back!

Your "... used successfully" caveat disqualifies me from replying (since I'm now constructing my first ROV). But I'll reply anyway. I see several advantages to onboard batteries. First, you won't have the line losses and voltage drops of long-distance low-voltage transmission. Second, tether buoyancy problems are much reduced by having no heavy conductors. Third, onboard batteries provide useful ballast.

On the negative side, onboard batteries require a fairly sizable container that is both reliably sealed and easily accessible. Maybe not such an easy trick.

My initial idea for battery type was Li-Ion. But battery vendors have scared me off them. You actually have to pass a test before they'll sell them to you! They're just flat-out dangerous, especially in novice hands. Depending on what mistake you make, you get to choose whether your shop burns down or is blown-up.

My current choice is Nimh. There is a 1.2 volt "F"-size cell (1.3" dia. x 3.7" long). 10 of them makes 12 volts. http://www.batteryspace.com has a lot of useful info on all types of batteries.

I invite comments on these ramblings. --Pilikia

For our ROV, we are supplied a 48V, 40A source at the surface and we plan on using DC-DC converters to output 24V. This will just be on the surface, and the voltage drop is acceptable for the thrusters. There is additional power conditioning and filtering for the control electronics which need 5V or 3.3V. Batteries would just take up too much room, and add a lot of extra weight and other problems to our design. Plus, I don't think that that is really an option for our team because of the MATE rules.

I prefer using a deep-cycle lead-acid "gel-cell" battery (that's a lot of dashes!). It is sealed, and meant for both indoor and outdoor uses. It does weigh a ton, but it lasts a very long time, and as long as you don't get water on it, you don't have to worry about anything like leaks. It is 12VDC, but if you get a "step-up" inverter, you should be able to up the voltage.

Unfortunately, I can't find my camera right now, else I would take a picture. Hope this helps...

I'm going to run power down (at least at first), but if your want onboard power nothing can touch the new Li-poly batteries for power density. You can wire them in a combination of series and parallel and fit fit packs of them into a piece of 4" PVC pipe. They are pricy, but the various RC hobbies love them so they are dropping in price fast. I found them fairly cheap here http://www.hobbyking.com/hobbyking/store/uh_listCategoriesAndProducts.asp?catname=Li-Poly+(All+brands)&idCategory=86&ParentCat=85

One thing to be aware of is that you have to use a special charger, as in you HAVE TO use a Li-poly charger or it will destroy the batteries, also they have absolute limits on how low they can be drained without ruining them, IIRC it's something like 30% (but double check that).


-Chance

I will be using surface power at the beginning, a rejuvenated car battery (Those new electronic chargers are well worth their cost!), but I have two 12V 7Ah Gell Cells waiting in the wings, so to speak, for version 2. Take note though that my umbilical will be less than 100 feet long, and that my thrusters will be powered through PWM motor drivers, i.e., losses via cabling are not one of my main worry.

But I will definitely build a version with inboard power, since this is the precursor to the next step, AUV.

I connected my Rov to a running diesel truck. Since I was testing in a pond all we had to do was pull the truck up and turn it on, hook up the wires to the trucks battery with jumper cables and it worked. It gave us unlimited time to test the Rov.

dual, im going to run a car battery from top side for thrusters and onboard packs for lights and camera. i am doing it that way because i get interfearence from the thrusters turning on and off on the vid feed, and theres too much powerdrop with the thrusters and lights going all at once.